Proxy 502 error on file upload with rails 2.3.2

I have the following running on a FreeBSD 6.0

Rails 2.3.2
Mongrel 1.1.5
Mongrel_cluster 1.0.5
Apache 2.2.8 with proxy balancer

After updateing to Raisl 2.3.2 i get a proxy error when uploading larger
files, You can se the error below: I have tested the setup with Raisl
2.2.2 and it works fine.

Does this have to do with Rack in the new Rails version?

(70014)End of file found: proxy: error reading status line from remote
server 127.0.0.1, referer: http://domain.com/admin/assets/new
[Wed Apr 22 09:30:37 2009] [error] [client xx.xx.xx.xx] proxy: Error
reading from remote server returned by /admin/assets, referer:
http://domain.com/admin/assets/new

/mattias